Internal-combustion engine



June 30, 1925.

F. MDLER INTERNAL COMBUSTION ENGINE Filed Feb. 17, 1923 frlnllllflflnm'irlllie l f f dnillnlllllfunalflr.uur,

Paiemed June 30,1925.

UNITED STATES PATENT oFFlcE.

FRANZ MDLEE, or EEELIN, GERMANY, AssIeNonI To MAEDLEE ENGINE' coaroEA-Y.'rIoN, oE CLEVELAND, oHIo, A coaPoEA'rIoN or MARYLAND.

ITERNAL-COMBUSTION ENGINE.

Application led February 17, 1923. Serial No. 619,772.

To all whom it may concern.'

Be it known that I, FRANZ MDLER, a c1t1- zen of Germany, residing at 21Einserstrasse, Berlin W., Germany, have invented controlling the aircharge under all condi tions of speed and load, and at the same timeautomatically utilizing the kinetlc energy of the exhaust gases to helpscavenge, cool and recharge the working cylinder.

When applied to a four or more cylinder two-stroke internal combustionengine, one feature of my invention comprises an ejector construction inthe exhaust passages, whereby the kinetic energy of the exhaust gasesautomatically helps to draw through the working' cylinders, in propersuccession, the required quantity of air for scavenging, cooling andrecharging the cylinders.

According to another feature of my invention, it is possible to regulatethe amount of air compressed in the working cylinder and regulate theprepared fuel charge so that the air charge bears such proportion to theinjected fuel charge that the combustible a mixture formed in theworking cylinder produces the best practical engine etliciency undervarying conditions of load and speed.

In order to insure the scavenging and recharging of .the workingcylinders under varying conditions of speed and load, Iprovide a blowerto help the kinetic energy of the exhaust gases draw the requisiteamount of air through the working cylinders. The degree of kineticenergy in the exhaust gases is in direct relation to the highestpressure reached in the working cylinder (at a given timing of theopening of the. exhaust port), and this pressure'depends upon thequantity of air enclosed therein for compression by the piston on itsinward movement and upon the quantity of fuel used. Given a correctexplosive or combustible mixture (I use the terms synonymously), thevelocity of the exhaust gases through the ejector construction referredto depends u on thedegree of ressure' reached in the wor ring cylinder.en the pressure 1n lthe cylinder is suiciently high, the exhaust gaseswillnhave volume and velocity suiicient to materially help scavenge,cool and-recharge the cylinder. Under certain conditions, the kineticenergy of the exhaust gases may be sufficiently high to relieve theblower entirely of its load. When' the press ure in the working cylinderis low, as under llght load or no-load conditions, the velocity of theexhaust gases is correspondingly low and .the load on the blower isincreased to prov 1de the air necessary to perform the requlredscavenging and recharging operations.v It will be understood that theblower is mechanically driven and absorbs power to operate it. Now, oneof the features of my invention permits the saving of a substantialportion of this power by utilizing the ejector action of the exhaustgases to cause scavenging and recharging alr to be brought through the.working cylinder, thereby relieving the blower from supplying all theair necessary for scavengmg and recharging. This lessens the load on theblower and consequently increases the mechanical efficiency of theengine.

In order to explain the principles and operation of my invention, I haveshown inthe accompanying drawings two illustrative embodimentscontaining the various features of my invention. For the sake ofsimplicity, these drawings are merely diagrammatic and show only so muchof an engine as is necessary for an understanding of my invention. Inthese drawings- Fig.' 1 illustrates diagrammatically, in cross-sectionthrough a single cylinder, a four-cylinder two-stroke engine'constructed in accordance with my invention; and

Fig. 2 is a similar view of a modication in which a turbo-blower and anejector exhaust manifold are shown attached.

In Fig. l, there is a working cylinder l. provided with a piston 3 andan exhaustport 5. The crank case 3 is adapted to be used as a blower'tosupply air through a pipe or passage 7 connected with a scavenging inletport 6. The pipe'7 is provided with a controlling device or valve 8,which can be turned to control the amount of aix' supplied to thecylinder by varying the priportion of air passing through 'thc opening 9into the atmosphere.

Connected` with vthe working c linder 1 through a channel is an auXiiary'cylinder 2 provided with a reciprocating pistion 4, which has abore or channel 16. The auxiliary cylinder 2 connects with a fuel-supplydevice through pipe 17, this device being shown on an enlarged scale atthe left of the auxiliary cylinder 2. The pipe 17 connects with apassage 13 formed in a threaded spindle 19. This spindle has an annulargroove 18 which connects with the transverse part of passage 18, sothat,

when the spindle 19 is screwed up or down, the connection betweenpassage 18 and the suction pipe 17 always remains open. The fuel iscarried from nozzle 20 by air or other gaseous medium sucked through thcopeningr 21 by the vacuum created in the auxiliary cylinder 2. Aregulating passage 22 is connected with the air or other gaseous mediumthrough a port 22. The regu'-l lating passage 22, controlled by athrottling member 23, leads into the annular groove 18 of the spindle19. The spindle 19 is equipped with a regulating handle or lever 14 forraising and lowering the spindle.

The scavenging and air charging valve 8 is controlled by a lever 10which is linked to lever 11 by a suitable connection 10. The lever 11 ispivoted to a fixed point 12', and is arranged to be controlled by themovements of a cam 13, pivoted at 12. A spring 11 holds the lever 11against the curved surface of cam 13. The cam\ 13 is connected to thelever 14 by a suitable connection 14', whereby the lever 14 and cam 13are adjusted to regulate the fuel and air .charge proportionately to thespeed and load of the engine. That is to say, when the valve 8 isoperated to vary the volume of air compressed in the working' cylinder,the lever 14 is controlled so as to-regula-te the quantity of fuelsucked by the vacuum into the auxil-v iary cylinder 2, so that at allspeeds and loads the most efficient mixture of fuel and air will beconsumed in the working cylinder. Cam 13 is operated in any convenientmanner.

The piston 4 in the auxiliary cylinder 2 is so arranged that when itvmoves outwardly a predetermined vacuum is created in the cylinder 2.Shortly after the auxiliary piston 4 reaches its bottom dead center,connection is established with pipe 17 and the vacuum'acts on thefuel-supply device to draw in a fixed volume of gaseous medium carryingwith it a predetermined amount of fuel. The vacuum is independent of theengine speed and produces a practically constant velocity of the gaseousmedium in the passage 18. The passage 18 is located directly over thefuel nozzle 20. By raising or lowering the spindle 19, thc

arca of the ai passage at the fuel nozzle is changed, so that thes eedof flow of the. air at the fuel nozzle, an hence the quantity of fuelcarried into the auxiliary cylinder 2by the air or gaseous medium Acanbe regulated independently of th'e engine speed and load.

Itshould be noted that, when the handle or lever 14 is turned, the cam13 is simultaneously swung around on its pivot 12, andl the lever 11 isdeflected by the curved surface of the cam. i This curved surface is soshaped and proportioned as to control the air inlet valve 8 in such amanuel' that the quantity of air compressed .in. the working cylinderwill always be such as will give the most eflicient combustible mixturewhen combined with the fuel injected from auxiliary cylinder 2 throughpassage 15. When the atmospheric pressure is different from that forwhich the engine is adjusted, 'or

when a fuel of different heat value is used, the quantity of air orgaseous medium let in through the regulating channel 22 can be varied bythe throttling member 23'for l the purpose of controlling the speed offlow of the air at the fuel nozzle 20. This does not affect theproportion of air units and hydrocarbon units confined in the workingcylinder at the various positions of the fuel and air control members.`

A serious drawback in two-cycle internal combustion engines hithertoproposed is that the burnt gases cannot be cleared out of the explosionchamber of the cylinder by scavenging air in a satisfactory manner. Thisdrawback is particularly serious in high Speed en ines in which thescavenging is performe by the piston of the engine itself or by aseparate pump. Another objection in engines of the present type, andparticularly in motor car engines, is that the explosive mixture isforced in and used for driving out the products of combustion left inthe ex losion chamber after the power stroke. uch engines can only beregulated in an unsatisfactory manner and they conx sume an excessiveamount of fuel.

In order to overcome the foregoing objections and difficulties, it is'necessary to scavenge the cylinder very thoroughly. The pressure bywhich the burnt gases are expelled should be as constant as possibleduring the `scavenging period, so as to remove the burnt residual gasfrom the cylinder in a uniform manner and to prevent. the formation ofeddies. Another requirement to be met is that the scavenging should beperformed with fresh air only, so as to obviate backfiring and losses offuel. Furthermore,

provision should be made forv the effective internal cooling oftwo-cycle engines, particularly in the case of air-cooled engines. Thecarburetor arrangements in use at the present day are unsuitable fortwo-cycle engines. In order to adapt the gas mixture toall possibleengine speeds, it 1s necessary to provide a method by which the mixtureof fuel and air is regulated so as to give the highest possibleefficiency at each particular speed and load.

These objects are accomplished by my in` vention, which enablestwo-,cycle engines to be constructed that fulfill all requirements whichan engine of high efficiency hasto lmeet In these engines, according. toa further feature of the invention, the kinetic energy ofthe exhaustgasesis utilized\to assist a blower in passing the greatest possiblevolume of air through the working cylinder for scavengiug'and rechargingpurposes. When the multiple eiector effect of the exhaust gases inmulti-cylinder engines is utilized, it is necessary to avoid appreci- 20able pressure fluctuations due to the rarefaction or partial vacuumproduced in the working cylinders, because otherwise oscillations willbe set up inthe exhaust Inani fold system which will give rise toconsider-l able resistances therein.

The invention also provides a positive regulation of the air and thefuel charge,`and the fuel charge is introduced into thev workingcylinder for the purpose-of forming an explosive mixture only when aproperly proportioned aircharge is enclosed in the working cylinder.

By passing a large volume of air through the cylinder, a veryconsiderable cooling of the working cylinder is accomplished. This isparticularly important in the scavenging of air-cooled engines. Since anincreased engine speed or Van increased combustion pressure in theworking cylinder entails a greater ejector efi'ept and the passingthrough the cylinder of a larger'quantity of air, an increase of load isaccompanied by a more effective cooling of the interior of the.cylinder. When the engine speed, or

the degree of pressure in the cylinder is very small, the ejector.effect is nil. The ejector action would also be disturbed by thefailure of a spark plug. Under these conditions," a turboblower lon theengine takes up the function of supplying the req uisite scavenging air.-Tliis turbo-blower offers practically no resistance. AThe twoy effects,the ejector effect and the blower effect, compensate each other, forwhen the engine speed is low, the scavenging is effected by theturbo-blower, and when the engine speed increases, the ejector effect ofthe exhaust gases begins to act. Scavenging lair fluctuations due toejector effect, and

such fluctuations as are produced by spark plug failures, are taken careof by the turbolower.

The foregoing features of my inventionare exemplified in Fig. 2, whichis an illustration. of the essential parts of a four cylinder two-cycleengine constructed ac.l

cording tomy invention. In the working cylinder 1 reciprocates a'working piston 2. When the piston l2 executes a downstroke, it opensthe exhaust port 18. After the exhaust gases have had time to expandthrough the pipes 3, the piston 2 opens the scavenging ports 17, vwhichare connected through a pipe 14 with the pipe 13 from the turbo-blower5. This pipe 13 also leads through a scavenging valve' 4 into theworking cylinder 1.- The exhaust pipes of the three other workingcylinders of the engine are-diagrammatically represented by 3, 3b and 3.An auxiliarypcylinder 8 has a piston 9 provided vwith'passages 10 and10a. ln the top dead center position of the piston 9, the passage 10 isconnected through a port 11 with the 'Working-cylinder. As soon as thepiston 9 starts to descend, it closes port 11. When the piston 9 is inits lowest position, the passagel 10 communicates with the suction pipe12 connecting with a fuel-supply device, which may be like that shown atthe left of Fig. 1. rlhe auxiliary piston 9 is driven by a crankarranged on a cam shaft 6. A cam shaft 6 carries a cam 7 to control thescavenging valve 4.

rlhe operation of the engine is as follows:

When the working piston executes a downstroke, it opens the exhaustports 18. Under full load, the exhaust gases expand at a speed of about800 to 900'meters per second. After the gas in the cylinder 1 hasexpanded, the scavenging ports 17 are opened and in this position thescavenging valve 4 also opens. On the return or upstroke of the piston2, the scavenging port 17 is closed first, then the exhaust ports 18 areclosed and then the scavenging valve 4 is closed at a predeterminedlater interval. Since the'exhaust periods in a four-cylindertwo-cycle`engine maybe made to overat a high speed, exert a sort ofejector effect on each other and produce a partial vacuum.

This partial vacuum. cannot become considerable, because, on account ofthe over lapping of the exhau'stperiods with each` other, the exhaustpipes are always in connection with one cylinder whose ports 17 andvalve 4 will be open. This partial vacuum draws air from the blower pipe13 through the cylinders. The blower 5 offers practically no resistance,so that an excessive vacuum in the cylinders is avoided. It isnecessary. to avoid oscillations in the exhaust pipe that would giverise to considerable resistance, therefore a continuous current is madeto flow through the exhaust Apipe which is constructed inmultipleejector erm.

When the engine runsslowly, the speed P of the pressure, the amount ofair supplied Vwhen the engine speed drops remams practically constant,because when the speed of revolution is slow the time which a unitquantity ofl air has for passing through the cylinder increases inproportion.'

Therefore, when the motor carries little or no load,- the scavengingaction is performed by lthe turbo-blower.' When-,the

' load increases, the ejector effect of theexhaust gases rises until, atthe maximum load, the highest vacuum is` produced and the load on theblower is at a minimum.

Since an-increase ofthe load (which env p tails an increased developmentof`heat in.

the engine) is accompanied by an increase of the quantity of air sentthrough the working cylinder, agreater cooling effect will beproduced inthe interior of the engine this effect rowing as the load increases.

This cooling e ect is very considerable, be-

cause about three to live times the piston-stroke volume of air can bepassed through the working cylinder after every power stroke.` At a lowspeed, the cooling 'of the interior of the cylinder falls off, be-

cause then the turbo-blower alone produces the scavenging lair and thisthen amounts to 11/2 to 1% times the volume of the piston stroke. Bythis arrangement, the temperature of the working cylinder is ke tconstant within narrow limits, and t is' enable the construction ofair-cooled motors for varying loads.

The air charge vin the working cylinder 1 is regulated by altering theangular position of the cam shaft 6 with the cam 7 in relation tothecrankshaft. When this is done, the closure of the scavenging valve 4takes 'place at a correspondingly dierent time. 'By the time the valve 4is closed, the piston 2 will, of course,lhave pushed some of the aircharge in the cylinder'l back into f the pipe 13. Hence, by altering thepoint of lengagement between the crank shaft and the cam shaft, anydesired amount of air can be caused, by mechanically controlled means,to be enclosed in the working cylinder. This regulation or 'control isindependent of the speed of rotation of the motor.

In Fig. 2, the piston 2v is shown in the.

actv of closing the exhaust ports 18.` On

the particular timing-shown in4 this diagrammatic view, the scavengingvalve 4` is also closed Aby the cam 7, so that this is the timing ofvalve 4 for enclosing the largest possible air charge in the cylinder.Also,

in this diagram, the timing of the pump piston 9 is so arranged that thepassage 10 is about to establish a connection betweenthe chamber 8 inthe auxiliary cylindcrand the main cylinder through the port 11. Whenthe channel 10 registers with -the port l1, the compressed fuel chargein chamber 8 is sprayed at constant velocity into the w'orking lcylinderinde endent of the engine speed and load, an combines with the aircharge in the working cylinder to form a combustible mixture.

When the main piston 2 continues its upstroke, in the particular timingarrangement shown as an illustrative example in Fig. 2, the enclosedmixture thus formed is compressed, While the piston 9 disconnects thepassages 10 and 11, and draws in a new fuel-charge. After the mixture inthe main cylinder is compressed, it is ignited by a suitable ignitionmeans. The spraying of the fuel into the workingl cylinder is performedonly after theA properv amount of air has 'been enclosed, in order toobviate all losses of fuel., Since the auxiliary piston drive and cam 7are timed in proper lrelationship to each other; the fuel 'charge can besprayed into the main cylinder only after the closure of valve 4,evenif` the point of engagement between the crank shaft and the camshafts 6 and 6 is altered. Obviously, the relativetiming of valve 4 andpump piston 9 canbe so adjusted that the fuel inJection takes place atany predetermined time after the closing of valve 4. In other words, theinterval between the closing of valve 4 and the injection of the highlycompressed fuel charge may be varied over a widel angle of crank shaftmovement, and this allows the prepared fuel to be injected at anypredeterminedmoment into` the less highly compressed air charge in theworking cylinder. i

Since the vacuum roduced during the outstroke of the aux' iary piston 94is always substantially the sameat all speeds of the engine, all that isnecessary to change the quantity of fuel introduced into the enat thefuel nozzle'by moving a lever or this member may also control therelationvgine is to alter the area of the air passage ship of the camshafts to the crank shaft, y i

so that the correct quantity of air is alwaysv enclosed in the workingcylinder to secure the highest possible working eiciency from theengine. I cla-imi l f 1. The method of increasing the eiciency oftwo-cycle internal combustion engines,

Ming

' comp'ress which com rises regulating the volume of air 'in the worcylinder, injecting a compressed repa fuel charge into the air chargeenc osed in the working cylinder, said air charge being at a lowerpressure than said compressed p/el char e, regulating the amountofinjected fuel c arge inv such proportion to the enclosed air charge thatthe resultant combustible mixture pro;

duces a power stroke of the highest practi-V cal efficiency at varyingspeeds and loads of the engine, causin a lower to maintain a sufficientsupply o air` for properly scavengin, cooling and recharging the workincylin er under varying condltions of loa and speed, and utilizing aportion of the kinetlc energy of the combustion gases tomelieve the loadon the blower.

2. The method of efficiently utilizing fuels of different heat values intwo-stroke inter nal combustion engines which comprises regulatingthe'volume o air compressed in the workin cylinder,'injectin acompressed prepared ue vcharge into t e less highly compressed aircharge enclosed in the workc linder regulating the amount'of injectelfuel charge in such proportion to the enclosed air charge that theresultant combustible mixture produces a power stroke of the 'highestpractical eliiciency at varying speeds and loads of the engine, varyingthe quantity of fuel prepared for injection in accordance with the heatvalue of the fuel used, so that the heat units (B.'t. u.) of theinjected fuel charge remain practically constant irrespective of thecharacter of the fuel used, causing a blower to maintain a suiiicientsupply of air for properly scavengingl cooling and rechargmg theworkingl cylinder under varying conditions l of loa and speed, andutilizing a portion of the kinetic energy of the combustion gases torelieve the load on thelblower.

3. In a two-stroke internal combustion engine, a working cylinderprovided with a piston and with admission and exhaust ports,controllable means for regulatino' the volume of air com ressed in thewolking cylinder, an auxillary cylinder provided with a piston andadapted to be connected with the working cylinder at predeterminedintervals, a .device for introducing into said auxiliary cylinder apredetermined quantity of fuel and a practically fixed volume of gaseousmedium, properly timed means for operating said auxiliary piston tocompress the mixture of fuel and gaseous 'medium in said auxiliarycylinder and to inject said compressed prepared fuel mixture into theair charge enclosed in the working cylinder at a lower pressure thansaid fuel charge, means for so controlling the percentage of fuel andair in the working cylinder that the resultant combustiblemixtureproduces a l lcylinder, an auxiliary power stroke of the highestpractical ellicxenc under var ing conditions of speed and oad, and alower operable to'pass a sufficient current of air through the workinglcylinder when .the exhaust ports. are open Ato 1plroperly scavenge,cool and recharge the wor ng'cylinden 4, In a two-stroke internalcombustion engine, a -working cylinder provided with a 4piston and withadmission and exhaust ports, controllable means for regulati the volumeof air com ressedVA in the wor in cylinder, an auxiliary c linderlprovide with a piston and adapte to be connected wlth the workingcylinder at predetermined lntervals, a device for introducing into saidauxiliary cylindera predetermined uantity of fuel and a practicallyfixed vo ume of gaseousmedium, properly timed means 1nto the less highlycompressed air chargel enclosed in the working cylinder means for socontrolling the percenta e of. fuel and a'ir in the workmg cylinder t atthe'. resultant combustible mixture produces' a power stroke of the hihest practical eicienc under varying con itions of speed and loa ablower operable to pass a sufficient c ent of air through the workingcylinder hen the exhaust ports are open to properly4 scavenge, cool andrecharge the working `cylinder, and connections whereby a rtion of thekinetic energy of the combiistion gases is utilized to relieve the loadon the blower and thereby assist in maintaining a suliicient supply ofair for properly scaveng.-v

ing, cooling and recharging the working cyl- 1n e under varyingconditions of load and spee 5. In a two-stroke ,internalAcombustionengine, a working cylinder provided with a pistonv and withadmission and exhaust. ports', controllable means for regulating thevolume of air-compressed in the workin c linder ,provide with a pistonand adaptedI to be connected with the working cylinder at predeterminedintervals, a device for introducing into said .auxiliary cylinder apredetermined quantity offuel and a practically fixed volume of 4gaseousmedium, properly timed means for operatmg said auxiliary piston tocompress the mixture of fuel and gaseous me ium in said auxiliarycylinder and to inject said compressed prepared fuel mixture `into theless highly compressed air char yenclosed in .the working cylinder,means or so controlling the percentageof fuel and air in the workingcylinderv that the resultant combustible mixture produces a power strokeof the highest practical elliciency under varying conditions ,ofV speedand load, means in said device for varying the quantity of fuelintroduced into sai auxiliary cylinder in accordance with the lieatvalue ofthe fuel used, so that the heat units (B. t. u.) of the injectedfuel charge remain practically constant irres ective of the character ofthe fuel use, an a blower operable to pass a suliicient current of 'airthrough the working cylinder when the ex-l haust ports are open toproperly scavenge, cool and recharge the workin cylinder.

6. In a two-stroke interna combustion engine, a working cylinderprovided with a piston and with admission and exhaust4 ports,controllable means for re ulatm the volume of air compressed in t epworln cylinder, an auxiliary c linder provide with a piston and ada te tovbe. connected with the working cylin er at predetermined n intervals, adevice for introducing into said auxiliary cylinder a predeterminedquantity of fuel and a practically ixed volume of gaseous medium,properly timed means for operating said auxiliar piston to compress themixture of fuel an gaseous medium in said `auxiliary cylinder andtoinject said compressed prepared fuel mixture into the less highlycompressed air char e enclosed inthe working cylinder, means or socontrolling the percentage of fuel and air in the working cylinder thatthe resultant com-- bustible mixture produces a power stroke of thehighest practical efficiency under varyin conditions of speed and load,means in sald device for varying the quantit of vfuel introduced intosaid auxiliary cy inder in accordance with'the yheat value of the fuelused, so that the heat units (B. t. u.) of the injected fuel 'chargeremain practicallypconstant irrespective of the character of the fuelused, a blower operable to pass a suiicient current of air through theworking cylinder when the exhaust ports are open to properly scavenge,cool and recharge the working cylinder, and connections whereby aportion Y of the kinetic energy of the combustion gases is utilized torelieve the load on the gaseous medium to draw fuel from said l nozzle,a separate passage above said gaseous medium, properly timed means forasian? operating said auxilia piston to compress QI the mixture offuelan us'medium in said auxiliary cylinder and to injet said compressedprepared fuel mixture into the less highly compressed air cha enclosedin the working cylinder, means or so controlling the percentage of fueland air in the working cylinder thatY the resultant combustible mixtureproduces a power stroke of the highest practical efliciency undervarying conditions of speed and load, means in said device for varyingthe quantity of fuel introduced into said auxiliary c linder inaccordance with the heat value of t e fuel used, so that the heat units(B. t. u.) of the injected fuel charge remain practically con- 30 stantirrespective of the character of the fuel used, and means forscavenging-and recharging `the working cylinder.

8. In a two-stroke internal combustion engine, a working cylinderprovided with a piston and with admission and exhaust ports, anauxiliary cylinder provided with a piston and adapted to be connectedwith the workin cylinder at predetermined intervals, a auxiliarycylinder a predetermined uantity of fuel andA a practically fixed vo umeof gaseous medium, properly timed means for operating said auxiliaryiston to com ress the mixture of fuel an gaseous me ium in saidauxiliary cylinder, means for 'injecting said compressed prepared fuelmixture at the pro er momentvinto the less highly vcompresse air chargeenclosed in the working cylinder, 'means for so controlling the 10percentage of fuel and air in the working cylinder that the .resultantcombustible mixtureproduces a power stroke of the highest practicaleflicienc under varyin conditions of speedjand loa means in sai devicefor va ing the quantity of fuel introduced into p sai auxiliary cylinderin accordance with the heat value of the fuel used, so that the` heatunits (B. t. u.) of the vinjected fuel charge remain practicallyconstant irrespecvtive of the character of the fuel used, and

means for scavenging and recharging the cylinder.

9.In an internal combustion engine, a

working `cylinder having a piston operable u therein, an auxiliarycylinder provided with a piston and adapted to be connected with theworking cylinder at predetermined intervals, mechanism for controllingthe introduction into said auxiliary cylinder of predeterminedquantity'of fuel and a practically fixed volume of gaseous medium, saidmechanism including a fuel nozzle, a regulable passage at said nozzle-forthe flow of a nozzle adapted to communicate with said auxiliarycylinder, said separate passage evice for introducing into said 9 aeingarranged to communicate with a source of gaseous medium supplyindependently of the gaseous medium which flows past said fuel nozzle,and an adjustable valve for controlling the amount of gaseous mediumtaken into the auxiliary Vcylinder through said separate passage,whereby the quantity of fuel carried into the auxiliary cylinder by thegaseous medium flowing past said l0 fuel nozzle can be varied'inaccordance with the heat value-of the fuel used, so that the heat units`(B. t. u.) of the injected fuel charge remain practically constantirrespective of the character of the fuel used.

In testimony whereof I ax my signature in presence of .two Witnesses.

FRANZ MADLER. lVitnesses MAX ABRAHAMSOHN, MARTHA HOLMBERG.

